Device for removing sea bed

ABSTRACT

A device for removing sea bed includes a conveying line at least partially surrounded by sea water and an emergency emptying device arranged in the conveying line. The conveying line is configured to have a sea bed be removed therethrough so that a removed sea bed is transportable to a surface in a conveying direction. The emergency emptying device is configured so that the removed sea bed moving in a direction counter to the conveying direction in the conveying line is dischargeable from the conveying line into the sea water.

CROSS REFERENCE TO PRIOR APPLICATIONS

This application is a continuation of application Ser. No. 14/236,908,filed on Feb. 4, 2014, which is a U.S. National Phase application under35 U.S.C. §371 of International Application No. PCT/EP2012/064199, filedon Jul. 19, 2012 and which claims benefit to German Patent ApplicationNo. 10 2011 052 429.0, filed on Aug. 5, 2011. The InternationalApplication was published in German on Feb. 14, 2013 as WO 2013/020788A1 under PCT Article 21(2).

FIELD

The present invention relates to a device for removing sea bed having aconveying line operated according to the airlift method, or using feedpumps, which is at least partially surrounded by sea water, and by whichremoved sea bed can be transported in the conveying direction to thesurface.

BACKGROUND

The “airlift method” is understood as the method for transportingremoved sea bed. The airlift method provides a supply of compressed airinto the bottom area of the conveying line. The air bubbles that rise onthe inside of the conveying line create the effect of an upward flow onthe inside of the drilling line that transports removed sea bed to amarine unit above the water line.

When such a conveying apparatus is employed for transporting mineral rawmaterials, such as, for example, manganese nodules from a water depth ofapproximately 5,000 m, the volume portion of the material transportedinside the conveying line can constitute up to 10% of the internalvolume of the conveying line. The conveying line can, for example, havean inside diameter of 40 cm.

It is regularly possible to generate a stronger upward flow if feedpumps are used. The volume fraction of the conveyed material is thengreater, however, the method tends to be even more susceptible toclogging.

If the conveying operation of removed sea bed comes to a standstill(irrespective of the reason therefor), the sea bed material that isinside the conveying line sinks very quickly to the bottom because ithas a considerably higher density than sea water. Assuming a water depthof 5,000 m and a volume fraction of removed sea bed of 10%, the resultis a 500 m long plug clogging the line. Freeing the conveying line ofthe plug by regular means is then either impossible, or only possiblewith great difficulty. Similarly, it is no longer possible to salvagethe conveying line due to the large mass of the plug, which can be asmuch as 1,500 to 2,000 t in the given example. In a worst case scenario,this means that the conveying line may need to be abandoned followingsuch an interruption of the conveying operation.

A reason for such an interruption can be, for example, a failure of atransport of flow inside of the conveying line. Such a failure can becaused by deposits of removed sea bed on the interior lining of theconveying line which gradually increase until they create a blockage ofthe complete internal cross-section or of the conveying line. Anotherconceivable reason for a blockage is an energy supply failure or acompressor failure which results in the compressed air necessary for theoperation of the airlift process no longer blowing into the conveyingline. If the sea bed is first pumped via solid-material pumps from aclearing vehicle to an interim station, which is also referred to as a“buffer,” and transported from there via the conveying line to themarine unit above the water line, defects on the submarine unit can alsoresult in a failure of flow transport. Extreme environmental eventshaving a propensity of causing an interruption in flow transport aremoreover conceivable.

DE 2008384 A describes a dual pipe conveying facility that has anannular pipe line with pipes that are routed as a sink pipe from theocean surface down to the ocean floor and as a lift pipe for thetransported material back up to the ocean surface. Pressurized waterpreferably circulates inside this annular pipe line as a transportfluid, wherein the pressurized water is circulated by pumps. Theconveyed material is fed into the annular pipe line via a pressure lockon the ocean floor. The pressure of the pressurized fluid is dimensionedsuch that the conveyed material fed into the annular line is raisedinside the lift pipe all the way to the water surface.

SUMMARY

An aspect of the present invention is to improve a device, as wasdescribed in the introduction above, where the clogging risk by theformation of a plug, accompanied by an interruption of operations or afailure of the transport of flow, is substantially reduced.

In an embodiment, the present invention provides a device for removingsea bed which includes a conveying line at least partially surrounded bysea water and an emergency emptying device arranged in the conveyingline. The conveying line is configured to have a sea bed be removedtherethrough so that a removed sea bed is transportable to a surface ina conveying direction. The emergency emptying device is configured sothat the removed sea bed moving in a direction counter to the conveyingdirection in the conveying line is dischargeable from the conveying lineinto the sea water.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in greater detail below on the basisof embodiments and of the drawings in which:

FIG. 1 shows a schematic representation of a view of a region of theconveying line around an emergency emptying opening, as seen in apartial longitudinal section; and

FIG. 2 shows a representation of the hydraulic diagram of an embodimentof the device according to the present invention.

DETAILED DESCRIPTION

The conveying line of the device according to the present inventioncomprise an emergency emptying means by which removed sea bed, which istransported counter to the conveying direction, can be discharged fromthe conveying line and into the sea water. This measure prevents theremoved sea bed, which is present inside the conveying line at the timeof the interruption or the failure of the transport flow, from forming aplug of the kind described above that becomes deposited in the line andclogs the bottom end of the conveying line.

In embodiment of the device according to the present invention, theemergency emptying means can, for example, comprise at least oneemergency emptying means that can be opened and closed, and throughwhich removed sea bed material moving against the direction of transportcan be discharged into the surrounding sea water.

To further accelerate such a discharge in order to further reducedown-times and any residual clogging risk, a plurality of emergencyemptying openings can, for example, be provided and, for example,disposed approximately at regular intervals over the length of theconveying line.

In an embodiment of the present invention, the openings can, forexample, be spaced every 200 m to 700 m, for example, at 400 m and 500 mintervals. Assuming that the removed sea bed inside the conveying linetypically sinks at 0.5 m/s following such a disruption of flow, theemergency emptying openings would have to remain open, for example, for13 to 17 minutes to provide an almost complete evacuation of removed seabed from the inside of the conveying line.

In an embodiment of the device according to the present invention, anemergency emptying door can, for example, be provided on each emergencyemptying opening. The emergency emptying door can be displaced into theinterior of the conveying line so that any removed sea bed movingcounter to the conveying direction can be discharged by the action ofthe emergency emptying door through the emergency emptying opening andinto the sea water.

A piston/cylinder apparatus that can be operated by water-hydraulicmeans can, for example, be provided for actuating the displacement ofthe emergency emptying door between the open and the closed positions.An advantage of a water-hydraulic actuation is that it isenvironmentally safe. If leaks occur, no hydraulic oil can escape whichcould damage the environment. It is moreover possible to omit a closedsystem for circulating hydraulic fluid altogether, because, whenpressure is to be relieved, the water is simply discharged into theenvironment and any return by way of a separate return line into thepressure reservoir can be omitted. The water-hydraulically operatedapparatus can therefore be conceived as having only a single, centralhydraulic supply for the totality of all piston/cylinder devices.

To avoid having to apply a continuous pressure to thewater-hydraulically actuated piston/cylinder devices during theconveying operation, the piston/cylinder devices are spring loaded sothat the emergency emptying doors move to their closed positions when nowater-hydraulic pressure is in effect. This means that only one pressureapplication to the piston/cylinder devices is necessary when thetransport of flow inside the conveying line comes to a halt due to amalfunction.

In an embodiment of the present invention, the hydraulic line can, forexample, be connected to a water reservoir that supplies thewater-hydraulic pressure. The hydraulic line can also include a closedwater tank that is filled with compressed air above the water level. Itis possible to connect the tank to a compressor that maintains theinternal pressure inside the tank at a preset value.

In an embodiment of the present invention, the hydraulic line connectedto a water reservoir can, for example, includes a free end that isclosed by a check valve. The check valve is disposed so that it opensagainst the pressure that is present inside the hydraulic line. Usingthis hydraulic line, the piston/cylinder devices are connected for thepurpose of actuating them against the spring force.

In an embodiment of the present invention, a switching valve can, forexample, be disposed between the water reservoir and the hydraulic linethat is able to execute the following switching positions:

-   -   Separation of the water reservoir from the hydraulic line by        means of a check valve that opens against the water-hydraulic        pressure provided by the water reservoir. This is the switching        position of the switching valve during a normal operation of the        device; i.e., when the desired conveyed flow is present inside        the conveying line.    -   Connection of the water reservoir to the hydraulic line. This        switching position can be manually actuated and, provided the        corresponding sensors are present, can automatically be actuated        in the event of a failure. In this switching position, the        pressure applied by the water reservoir to the water in the        hydraulic line actuates the piston/cylinder devices against the        spring pressure so that the emergency emptying doors are        displaced to the inside of the conveying line for the purpose of        discharging removed sea bed to the outside.    -   Separation of the water reservoir from the hydraulic line and        simultaneous closing of the water reservoir as well as opening        of the hydraulic line to the environment. The switching valve is        brought in this position when the conveying operation must be        restarted after a disruption in the conveying operation has been        remedied, and/or after the material that is inside the conveying        line was discharged into the surrounding sea water by opening        the emergency emptying openings.

The present invention will be described in further detail below based onthe drawings.

The embodiment of a device according to the present invention, asdepicted in the drawing, comprises a conveying line 1, a section ofwhich is shown in FIG. 1. The conveying line 1 is approximatelypipe-like with an inside diameter 2 of 2 to 40 cm. The conveying line 1serves to transport removed sea bed to the surface using the so-called“airlift method.” Mineral raw materials are in particular conceivable asremovable sea bed, such as, for example, manganese nodules that aremined at an underwater depth of approximately 5,000 m. The length of theconveying line 1 is therefore approximately 5,000 m.

Using the airlift method, an upward fluid flow is created on theinterior 3 of the conveying line 1, as symbolically indicated by thearrow S.

To avoid large quantities of removed sea bed becoming impacted at thelower end of the conveying line 1 and forming a plug if the operation isinterrupted due to a failure in the transport of flow, emergencyemptying means 4 are provided, respectively spaced at 500 m intervals.

The functionality of these emergency emptying means 4 shall be describedin further detail below in reference to FIG. 1, which depicts saidemergency emptying means 4 in the activated state.

In section B, which is where the emergency emptying opening 5 islocated, the conveying line 1 has an approximately oval cross-section.Below the emergency emptying opening 5, a bearing means 7 is provided onthe outside of the wall 6 of the conveying line 1, where an emergencyemptying door 8 of the emergency emptying means 4 is connected in anarticulated manner and can be pivoted about a hinge axis T that isarranged transversely relative to the longitudinal extension L of theconveying line 1. The emergency emptying door 8 can be pivoted from aclosed position, in which the emergency emptying opening 5 is completelyclosed and the emergency emptying door 8 is substantially flush with thewall 6 of the conveying line 1, to an open position, as depicted in FIG.1, in which the emergency emptying door 8 rests by the remote edge 9thereof relative to the hinge axis T internally against the wall 6 onthe side that is opposite the emergency emptying opening 5, thereinforming an opening angle α of approximately 30° with an opening plane.

A water-hydraulically powered piston/cylinder apparatus 10 is providedfor the pivot actuation between the closed and the opened positions. Thepiston/cylinder apparatus 10 engages via a piston rod 12 via a lever 11,which protrudes approximately perpendicularly from the surface of theemergency emptying door 8. A cylinder-side end of the piston/cylinderapparatus 10 is fastened to a bearing projection 13, again on theexterior of the wall 6.

A compression spring 15 is disposed in the annular space between thepiston rod 12 and a cylinder space 14. The compression spring 15 causesthe piston rod 12 to be supported in a retracted position when theemergency emptying door 8 is flush with the wall 6 so as to seal theemergency emptying opening 5 when no pressurized water is applied to thecylinder space.

In the position of the emergency emptying door 8 as depicted in FIG. 1,removed sea bed is guided in the form of solid material particles 16,which are symbolized by the circles as presently shown in FIG. 1, whilesinking as a result of a malfunction or interruption of the transport offlow within the meaning of the arrows P, and discharged toward theoutside into the surrounding environment of the conveying line 1. Due tothe fact that a typical sink rate of the removed sea bed (as previouslydescribed) is approximately 0.5 m/sec, an accumulation of the sunken seabed material in the ambient area surrounding the bottom end of theconveying line 1 can be precluded because even small ocean currents thatare in effect outside of the conveying line 1 will cause the material tobe distributed over a large terrain.

The apparatus that is provided for the water-hydraulic actuation of thepiston/cylinder apparatus 10 and the emergency emptying door 8 shall bedescribed in further detail below in reference to FIG. 2.

In FIG. 2, O designates the sea water surface. For actuation purposes,the cylinder chambers 14 of the piston/cylinder devices 10 are connectedto a hydraulic line 18 via the supply lines 17. As can be seen in theschematic sectional representation in FIG. 2 of the piston/cylinderdevices 10, the compression spring 15 operates in an embodimentaccording to FIG. 2 with an effect on the floor of the piston on a sidethat is opposite of the piston rod 12. The cylinder volumes arecorrespondingly formed by the annular space that surrounds the pistonrod 12. This configuration, that is reversed in relation to theembodiment according to FIG. 1, has the advantage of a lesser cylindervolume filled with hydraulic fluid, such that, due to the returndisplacement of the pistons that is effected by the compression springs15 as well as for the displacement of the pistons due to thewater-pneumatic pressure, only smaller amounts of water must betransported, whereby it is possible to reduce the actuation times.

The hydraulic line 18 is hydraulically connected to a water reservoir 20by way of a switching valve 19. A measurement means 21 is disposedbetween the switching valve 19 and the water reservoir 20 which measuresthe amount of the flow-through and the pressure that the water issubject to within the hydraulic line 18.

The water reservoir 20 comprises a pressure tank 22. The pressure tank22 is filled with water to a filling level 23. A freely movable piston38 is disposed above the filling level 23, and a compressed air cushionis in effect acting upon the same, whereby the air cushion is generatedwith the aid of a high-pressure piston compressor 24 that is connectedvia a high-pressure air accumulator 25 to the pressure tank 22, which isalso referred to as the “piston accumulator.” A pressure measurementinstrument 26 and a pressure relief valve 27 are activated in the supplyline to the pressure tank 22. The pressure line that runs between thehigh-pressure piston compressor and the high-pressure air accumulatorsis also provided with corresponding means 28.

The water reservoir 20 further comprises a fresh water tank 29 fromwhich, via a line, which is protected with the aid of a check valve 30against reflux, a high-pressure water pump 31 pumps pressurized waterinto the pressure tank 22 to achieve and/or maintain the desired fillinglevel 23. A bypass 32 is switched between the high-pressure water pump31 and the hydraulic line 18 that leads to the fresh water tank 29,which is connected to the line via a stop cock 33 and a pressure reliefvalve 34.

If a malfunction or interruption of the transport of flow is detected inthe conveying line 1, triggering an emergency switch 35 that engages theswitching valve 19, which is actuated manually or via suitable sensors(which are not shown in the present drawings), and which measures thetransported flow inside the conveying line 1, results in the switchingvalve 19 being moved into the switching position III. In this switchingposition, the hydraulic line 18 is connected to the pressure tank 22.Due to the pressure increase, water flows into the cylinder chambers 14of the piston/cylinder apparatuses 10 which are thereby actuated againstthe effect of the compression springs 15, thus causing the emergencyemptying doors 8 to open. Sinking solid material particles 16 aredeflected laterally through the emergency emptying openings 5 to theoutside, as described above.

To close the emergency emptying openings 5, employing suitable means,the switching valve 19 is moved into switching position II. In thisposition, the supply line from the pressure tank 22 is closed by thehydraulic line 18. The hydraulic line 18 is open toward the environmentand/or a fresh water reservoir, which can be a fresh water tank 29. Dueto the retractive forces generated by the compression springs 15, theemergency emptying doors 8 are moved to the closed position with the aidof the piston rods 12. After reaching said position, the switching valve19 is moved into the resting position I as depicted in FIG. 2, when thehydraulic line 18 is connected by a check valve 38 that opens againstthe water-hydraulic pressure as provided by the water reservoir 20 witha fresh water reservoir 29.

The hydraulic line 18 includes an end 36 that is free relative to theenvironment. It is closed via a check valve 37 that must be openedagainst the pressure that is present inside the hydraulic line 18.

The present invention is not limited to embodiments described herein;reference should be had to the appended claims.

LIST OF REFERENCE NUMBERS

-   -   1 Conveying line    -   2 Inside diameter    -   3 Interior    -   4 Emergency emptying means    -   5 Emergency emptying opening    -   6 Wall    -   7 Bearing means    -   8 Emergency emptying door    -   9 Edge    -   10 Piston/cylinder apparatus    -   11 Lever    -   12 Piston rod    -   13 Bearing projection    -   14 Cylinder chamber    -   15 Compression spring    -   16 Solid particle materials    -   17 Supply lines    -   18 Hydraulic line    -   19 Switching valve    -   20 Water reservoir    -   21 Measurement means    -   22 Pressure tank    -   23 Filling level    -   24 High-pressure piston compressor    -   25 High-pressure air accumulator    -   26 Pressure measurement instrument    -   27 Pressure relief valve    -   28 Means    -   29 Fresh water tank    -   30 Check valve    -   31 High-pressure water pump    -   32 Bypass    -   33 Stop cock    -   34 Pressure relief valve    -   35 Emergency switch    -   36 End    -   37 Check valve    -   38 Check valve    -   α Opening angle    -   B Section    -   F Direction of transport    -   L Longitudinal extension    -   O Sea water surface    -   P Arrows    -   S Arrow    -   T Hinge axis

What is claimed is:
 1. A device for removing sea bed, the devicecomprising: a conveying line at least partially surrounded by sea water,the conveying line being configured to have a sea bed be removedtherethrough so that a removed sea bed is transportable to a surface ina conveying direction; and an emergency emptying device arranged in theconveying line, the emergency emptying device being configured so thatthe removed sea bed moving in a direction counter to the conveyingdirection in the conveying line is dischargeable from the conveying lineinto the sea water.
 2. The device as recited in claim 1, wherein theemergency emptying device comprises at least one emergency emptyingopening configured to be opened or closed and to laterally discharge theremoved sea bed moving in the direction counter to the conveyingdirection from the conveying line into the sea water.
 3. The device asrecited in claim 2, wherein the emergency emptying device comprises atleast two emergency emptying openings.
 4. The device as recited in claim3, wherein the at least two emergency emptying openings are arranged atregular intervals over a length of the conveying line.
 5. The device asrecited in claim 3, wherein the at least two emergency emptying openingsare arranged so as to be spaced every 200 m to 700 m.
 6. The device asrecited in claim 3, wherein the at least two emergency emptying openingsare arranged so as to be spaced every 400 m to 500 m.
 7. The device asrecited in claim 2, further comprising an emergency emptying doorarranged at each emergency emptying opening, the emergency emptying doorbeing configured to move so as to open the emergency emptying openingtowards an interior of the conveying line so that the removed sea bedmoving in the direction counter to the conveying direction isdischargeable via the emergency emptying door though the emergencyemptying opening into the sea water.
 8. The device as recited in claim2, further comprising a piston/cylinder apparatus configured to beactuated by a water-hydraulic pressure and to move the emergencyemptying door.
 9. The device as recited in claim 8, wherein thepiston/cylinder apparatus comprises a compression spring configured tomove the emergency emptying door into a closed position when nowater-hydraulic pressure is applied.
 10. The device as recited in claim8, further comprising a water reservoir configured to provide thewater-hydraulic pressure.
 11. The device as recited in claim 10, whereinthe water reservoir comprises a hydraulic line configured to connect thepiston/cylinder apparatus so as to actuate the piston/cylinder apparatusagainst a force of the compression spring.
 12. The device as recited inclaim 11, wherein the hydraulic line comprises a free end and a checkvalve, the check valve being configured to seal the free end.
 13. Thedevice as recited in claim 10, further comprising: a switching valvearranged between the water reservoir and the hydraulic line, theswitching valve being configured to activate a switching state selectedfrom: a separation of the water reservoir from the hydraulic line via acheck valve configured to open against the water-hydraulic pressureprovided by the water reservoir; a connection of the water reservoirwith the hydraulic line; and a separation of the water reservoir fromthe hydraulic line, a closing of the water reservoir, and an opening ofthe hydraulic line to a surrounding environment.